I need help with this question. Its another dot product question. But this time I actually have no idea where to begin. It seems like there is so little information to go off of.

Question

cbreadbox · Answer

attachment

jim_thompson5910 · Answer

rule:

$$\Large u \cdot v = ||u||*||v||*\cos(\theta)$$

where u and v are vectors and theta is a scalar

cbreadbox · Answer

That was easier than I thought is was going to be. 
5*4*cos45=14.14

jim_thompson5910 · Answer

14.14 is correct

cbreadbox · Answer

@jim_thompson5910 
I need your help with one more thing. Isn't this the same question I just solved?

jim_thompson5910 · Answer

yeah but they didn't give you the value of theta. How cruel of them

jim_thompson5910 · Answer

I have a feeling they copy/pasted the problem but forgot theta = pi/4

jim_thompson5910 · Answer

but it's impossible to say, maybe they meant another value of theta

cbreadbox · Answer

Great. Glad this is my last year. Thanks for the help!

jim_thompson5910 · Answer

I'd just ask the teacher and s/he'll fix it

cbreadbox · Answer

okay, ill probably have to do that.